Motor-control system.



J. P. TRITLE.

MOTOR CONTROL SYSTEM.

APPLICATION FILED NOV. 14, 1908.

Patented Apr. 6, 1909.

TN SZEHTUH JOHN F THZ'TLE'. fl/

Will/@5555.-

A TT' Maw.

UNITED STATES PATENT QFFICE; JOHN F. 'lRIlLE, OF SGHENEGTADY, NEW YORK,ASSIGN OR TO GENERAL ELECTRIG COM-1 PANY, A CORlORATION OF NEW YORK.

To all whom it may concern: i p p Be it known th at I, J OHN F TRITLE, aciti- Zenof the United States, residing at Schenctady, county ofSchenectady, State of New York, have invented certain new and usefulImprovements in Motor-Control Systems, of which thefollowing is aspecification.

My invention relates to the control of elec tric motors'by means ofresistances and is particularly useful in connection with the control ofa plurality of electric motors driving acommon load. lVhile its broadaspect it is not limited to the control of induction motors, itispartic'ularly applicable to motors of that type having resistances incircwt with their respective secondaries, which resistances are cut outstep-bystep as the motor starts. It has been customary heretofore in thecontrol of a plurality of such motors arranged to drive a common load,such as a locomotive, car or other vehicle, to employ electricallycontrolled switches for successively short circuiting correspondingportions of the resistances for the severa motors, said switchesbeingcontrolled from a suitable master switch.

- Broadly considered, the object of my invention is tomako smoother theacceleration of vehicles driven by a plurality f motors.

To this end, my invention, in oiihparticular embodiment, consists in soarrangin the short circuiting switches and the contro circuits thereforthat in certain positions of the masterswitch certain of thecorresponding switches for the several motors will close automaticallyin succession instead of simultaneously. \Vith such an arrangement thevarious motors of the vehicle will not be accelerated step-by-step atexactly the same instant and the resulting acceleration of the vehiclewill be smoother than under present practice where all of the switchescontrolling corresponding sections of resistances for the various motorsclose at the same time.

In carrying out my invention I provide the.

Specification of Letters Patent.

Application filed November 14, 1908.

Patented April '6, 1909.

Serial No. 462,561.

trol system arranged in accordance with my invention.

- lhe drawingshows diagrammatically amotor control system adapted forthe control of two polyphase induction motors drivmga vehicle or othercommon load.

A represents the, current collectors or trolleys which are shown as.ofthe bow trolley type.

B represents main switches in series with.

the primary windings of the step clown transformer C, to the secondarywindings of which the primary windings D and D of themotors M and M areconnected. 1C

The secondary windings of the motors M and M are indicated atlt and E,in circuit with which are connected sections of resist ance R to lthrough collector rings e, e, e e e", and e. The arrangement of theresistances shown is the three-phase Y connection comprising in the caseof each motor three groups of resistance, one in each phase,

the groups ofthe motor M having a common terminal f and the grou s ofthe motor M have a common termina f. For the sake of simplicity inillustration I have shown a system in which each group of resistancescomprises but two resistance sections, but

obviouslyany desired number might be employed; I

In the particular system shown, 1 to 12 inclusive indicate electrically"controlled switches arranged to short circuit the sec-' tions ofresistance under the control of the master switch K, diagrammaticallyindi: cated in a usual conventional manner. For the sake of simplicitythe master-switch has been shown as serving simply to control theresistance controlling switches, the switch S being shown as serving toconnect the primariesv of the motors to the secondaries of thetransformer C; it is obvious, however,

that the master-switch K would in practical operation be arranged toclose, in its 1st. p0- sitlon, line switches corresponding to the switchS.

T he master-switch K comprises seven sta j',

tionary contact fingers g to g inclusive, said fingers being arranged tocooperate with segments on a drum having 6 positions indicated by thedotted lines 1 to 6. Thebgments of the master-switch are allelectrically connected and the stationary finger g and its cooperatingsegment serve in all on positions of the master-switch to connectthesegments to one phase of the source through the wire 15 as shown. Thefingers g? to g inclusive are connected through control wires, as shown,to the actuating coils of the electrically controlled switches i to 12inclusive, certain of said switches being provided with interlockingswitches, shown. in the usual diagrammatic manner, which control theenergization of the actuating coils of the electrically controlledswitches in a manner which will now be described.

l fhen the switch S is closed, the masterswitch K being in. its oilposition as shown, the primary circuits of the motors M and M areconnected to the sec-n" dariesof the transformer C and the motor startwith all of the resistances in their socoi .dary circuits. i i' hen themaster-switch K is moved to its let on position, the contact lingers gand g are connected together, thereby causing the energization of theactuating coils of the switches 1 and 2 the circuit for the former beingcom pleted through interlocking switch Z on the switch 7 arranged to beopened by the latter when it closes. Closing of the'switches .i and 2results in the simultaneous short circuiting oi the sections ofresistance R and R located, respectively, in one of the phases of thesecondaries of the motors M and M. In the 2nd position of themastenswitch K the actuating coil of the switch 3 is energizedthroughthe interlock Z on the switch 9, and the actuating coil of the switch 4:is also energized; the switches 3 and 4', therefore, close; Switches 3and l in closing short circuit sections of resistance ll and li located,

respectively, in another phase of tho sccondcries of the motors M andBI. In the 3rd position of the 1nastcrswitch K the act uating coil ofswitch 5 is energized through the interlock Z on theswitch l1, and theactuating coil of switch 6 is simultaneously energized;

switches 5 and 6, thcrclorc, close at the same time. Switches 0 and 6short circuit sec tions of resistance R and It located, respectively, ina thirdphnse of the secondaries ofthe motors \l and M respectively Up tothis point the sections of resistance in the secondary circuits of lhemotors have been short circuited in the usual order; that is, sectionsof resistance in corresponding phases of the-secondaries of the motorshave been short circuited simultaneously. During the further movement ofthe mastel switch K, however, the short circuitiug of the sections ofresistance in the secondaries of the various motors will take place notsimultaneously but in succession with a short interval of timeintervening. In the 4th position of the mastenswitch h: the actuatingcoil of the sir,

Wit

tcr-switch reaches those positions.

switch 7 is at once energized and this switch closes, thereby shortcircuiting the sections 3 of resistances R" and R in one phase of the isecondary of the motor M. The switch 8,

the actuating coil of the switch 8 is energized and this switch closes,thereby short circuiting the sections of resistances R and R in one haseof the secondary of the motor'M.

lithis arrangement it is clear that a certain interval of time mustelapse between closing of switch 7 and closing of switch 8 and theirsimultaneous closing is impossible.

As the switch 7 short circuits both sections R and R, no eiiect. movedto its 5th position the finger y engages with its cooperating segmentand the actuetnig coil of the switch 9 is energized, thereby causingthat switch to close, which .in closing opens its interlock Z andinterrupts the circuit through the actuating coil of the switch 3. Theswitch 10 will not close simultaneously with the switch 9, since itsactuating coil will be energized only after the switch 3 has opened andclosed its interlock Z. The switches 9 and 10 will therefore close insuccession as in the case of switches 7 and 8. Switches 9 and 10 shortcircuit, respectively, resistance sections R R and it it. there is noneed for maintaining the switch 2 closed, the segment which cooperateswith the finger {1' may be omitted in the 5th and 6th positions of themaster-switch, thereby allowing the switch 2 to open after the mas- Inthe 6th position of the maste1'-s\ vitcl1, the switch 11 is first closedand the switch 12 closes a little later, after the switch 5 has openedand closed its interlock 1 following the interruption of the circuitthrough its actuating coil by the opening of the interlock 1", theconnection closed by'the switch 5 being no longer necessary owing to theclosing of the switch 11. Switches 11 and 12 inclosing short circuit,respectively, resistance sections R R and R R cooperating with themotors M and ill. In this position of the masterswitch the finger ceasesto engage with its cooperating segment and the switch 4 is allowed toopen.

It will be clear from the above that in the first three positions of themaster-switch K the resistance sections in certain phases of thesccondariesof the motors M and M will be short circuited simultaneously,while in the 4th,- 5th and 6th positions of the master- Since after theswitch 8 has closed opening of the switch 1 will have hen themaster-switch K is switch the resistance sections in the'phases of thesecondaries will be short circuited not simultanee'd 'ly but successivelwith an interval of time iDt6IV6I1lI1g, t1e length of which do end'supon the rate at which the electrical y controlled switches open whendeenergized. It is clear, therefore, that, al-

though the master-switch has but six on positions, acceleration of thevehicle as 'a whole will take place in nine steps resulting of motorshaving resistances with any numher of sectionsconnected in thephases oftheir secondaries. For example, in the case ofiour. motors withresistances in the phases of their secondaries having two sections eachand with a master-switch having six ositions, as inthe arran ementshown, the e ective number of acce'eration steps would be fifteen.Likewise, with two motors having resistances made up of three sectionsin each phase of their secondaries and with a nine point master-switch,fifteen efiective accelcrating steps may be obtained. Or with fourmotors having resistances made up of three sections in the phases oftheir seconda'riesand with a nine point switch, twent seven effectiveaccelerating steps will e obtained. 1

It is obvious that, if desired, interlocks mi ht be provided on theelectrically contro led switches and so arranged that even in the firstthree positionsof the masterswitch the switches which short circuit thesections of resistance for the various motors, will close notsimultaneously but successively. That is, the circuit to the actuatingcoil of a switch co'o' crating with one motor might be led throug 1 aninterlock closed by the, corresponding switch cot) crating with theother motor when the atter switch closes. Since, however, theelectrically controlled switches usually employed close so much morequickly than they open, the time interval given by such an arrangementbetween the closing of correspondin switches would be very short, andprobab ly the results obtained would not warrant the increasedcomplication of circuits. Inorder to get the propergradation ofacceleration the resistance sections should be properly pro ortioned, aswill be understood y those sk' ed in the art.

I do not desire to limit myself to the particular construction andarrangement ofparts here shown, but aim in the appended" claims to coverall modifications which are within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is 1. In combination with a plurality of motors, resistances incircuit with the several motors, switches arranged to short circuitsections of said resistances, and meansfor causing successive closing ofcorresponding switches for the several resistances.

2. In combination with a plurality cf motors, resistances having aplurality of sections in circuit with the'several motors, as manyswitches as there are sections of resistance arranged to short circuitsaid sections of resistance, and means for causing successive closing ofthe' switchcs which short circuit corresponding sections for all theresistances.

3. In combination with a plurality of electric motors, resistances incircuit with the several motors, electrically controlled. switchesarranged to short circuit sections of the resistances, a master-switchfor con- I trolling the operation of corresponding so switches for allthe resistances,'and means for causing successive closing ofcorresponding switches. v

4. In combination with a plurality of electric motors, resistances incircuit with the several motors, electrically cont-relied switchesarranged to short circuit sections cf said resistances, a master-switchfor control lingthe operation of corresponding switches for all theresistances, and means for causing automatic successive closing ofcorresponding switches.

5. In combination with a plurality of electric motors, resistances incircuit with the several motors, electrical-1y controlled 1'05 switchesarranged. to short circuit sections of said resistances, a master switchfor controlling the operation of corresponding switches for all the.resistances, and means including interlocks on the said switches forcausing 1/10 automatic successive operation of corresponding switches.

6. In combination with a plurality ofmotors, resistances in circuit withthe several motors, electrically controlled switches a'rranged to shortcircuit greater and greater portions of the resistances for the severalmotors beginning at the same point on each resistance and extending inthe same direction, control circuits for said switches, and interlockingswitches cooperating with said first mentioned switches and con-trollingsaid control circuitswhereby certain corresponding switches forjtheseveral resistances cose automatioallyi insuccession.. a 7. Incombination with a plurality of mo tors, resistancesin circuit with theseveral motors, electrically controlled switches ar rangedto shortcircuit successively greater portions of the several resistances,a'master switch for controlling the operation of corresponding switchesror all the resistances, interlocking switches operated by certain ofsaid electrically controlled switches located in the control circuitsfrom said master- 'switch to said switches whereby closing of certainswitches which short circuit por tions of said resistances cause theopening of the switches which short circuit portions of said resistancesincluded in the portions short circuitcd by the first named switches,

and interlocking switches operated by said coiipcrating w th saidswitches and located last mentioned electrically controlled switcheswhereby opening of the latter causes closing of certain electricallycontrolled switches for another resistance.

8. In combination with a plurality ol elecei'mea rality of sections ofresistance for another motor upon the opening of a switch shortcircuiting the single section of resistance for the first named motor.

10. In combination with two inotors,-a resistance in circuit with eachmotor, electrically controlled switches arranged to short circuitsuccessively greater portions of each resistance beginning at the samepoint on each resist ance, a master-switch for controlling the operationof corresponding switches for h t h resist anccs, and interlockingswitches in certain control circuits therefor whereby closing ot aswitch short circuiting a portion of the resistance cooperating with tiefirst tric motors, resistances having a plurality of I sections incircuit with the several motors, electrically controlled switchesarranged to short circuit single sections of resistance, electricallycontrollml switches arranged to short circuit a plurality of sections ofrcsistance including the sections short circuited by the first mentionedswitches, a

master-switch for controlling the operation of corresponding switchesfor all the resistinotor causes the switch which has short circuited asmaller )ortion of that resistance to open, and wherchy opening of saidlast mentioned switch causes closing of the switch for the otherresistance corresponding to the first mentioned switch cooperating withthe first resistance.

1], In combination with a plurality of in- 1 duction motors, three-phasearrangements oi resistances connected in \5" in series with thesecondaries ol the several motors, electrically ances, interlockingswitches operated by the various electrically controlled switcheswhereby closing of a switch which short circuits a plurality ol'sections causes the opening ol' the switch which short circuits one ofthose sections and whereby opening of 5 cession.

said last mentioned switch. causes the closing of the switch which shortcircuits a plurality of sections of resistance for another motor,

9. In combination with a plurality of electric motors, resistanceshaving a plurality of sections in circuit with the several motors,

electrically controlled switches arranged to short circuit singlesections of resistances, electrically controlled switches arranged toshort circuit a plurality of sections of resist-- ance including thesections short circuited by said :lirst named switches, a master-switchfor controlling the operation of corresponding switches for all theresistances, control circuits between said master-switch and said fsuccession including interlocking switches switches, and interlockingswitches operated by certam 0t said electrically controlled switchesarrai'igcd to interrupt the circuit through the actuating coil of aswitch short circuiting a single'section of resistance for closed, andto complete the actuating circuit for a switch arranged to short circuita pin controlled switches arranged to short circuit portions of saidresistances for the several motors, and means for easing certaincorrespending switches for the resistances in col responding phases ofthe secondaries of the several motors to close automatically in suc- 12In combination with a plurality of in duction motors, three-phasearrangements oi resistances connected in Y in series with thesecondaries of the several motors, electrically controlled switchesarranged to short circuit portions of said resistances for the severalmotors, a master-switch. for controlling the operation of said switchesso as to short circult corresponding nortions of said resistanees incorresponding phases of the sec ondaries of all the motors in thevarious posi- 'tions of said mastcr-switch, and means forautomz'itically causing certain corresponding switches lor the severalresistances to close in operated by said linsnt named switches.

In witness whcrcol', l have hereunto set hand this 12th day oi November,1908.

JOHN F. TRIPLE.

Nitnesses:

BENJAMIN 8. ne

HELEN ()RFORD.

